Previous trials have demonstrated significant antitumor activity of interferon alfa in patients with cutaneous T-cell lymphomas. The dose used in the original trial was the maximally tolerated dose of 50 million units per meter squared given intramuscularly three times per week. The response rate in that trial was approximately 50 percent, and all responses were partial responses. All patients required dose reductions because of progressive interferon-related toxic side effects. In this protocol, we attempted to administer interferon cyclically at a dose of 50 million units per meter squared intramuscularly daily for four consecutive days (following an initial dose of 10 million units/m2 on day 1) every third week. The hope was that patients would recover from interferon-related side effects and that the amount of interferon actually delivered to patients might be increased by administering the therapy in this manner. If this was possible, higher response rates might be attained. Twenty-four patients were entered of whom 22 are evaluable for response. There was one complete remission lasting 7+ months, six partial remissions lasting a median of 7.5 months, six minor responses, and nine patients without response. In the first twelve weeks of therapy, 94.5 percent of the projected total dose of interferon had been administered reflecting reasonable patient tolerance to this different schedule of interferon administration. This compares to a less than 50 percent projected delivery of drug in patients treated with 50 million units intramuscularly three times per week on the older protocol. The similar overall response rate to the original study suggests that there is no dose-response relationship of this disease with interferon alfa at least over the dose range examined.